Following the 7 October 2023 attacks, scholars have offered myriad legal views arising from the ongoing hostilities. What is missing from these debates is an exploration of the “dark side” of International Humanitarian Law (IHL), which, as classically conceived, was not developed for urban wars or for conflicts between states and armed groups resisting occupation or colonialism. It was originally developed in the late nineteenth century on a clear distinction between the international (European) and colonial spheres. According to this distinction, conflicts between so-called civilized states were wars in the legal sense, unlike civil and colonial wars that were left to the realm of discretion and exception. In exploring the “dark side” of IHL, this article addresses how the law is being used, discursively, to make ethical and moral judgements about battlefield practices, through the constant articulation of claim and counterclaim by employing dehumanising language to justify the mass killings of Palestinians in Gaza. For the term “savage” implies a legal/moral judgement, as does the denial of POW status to so-called “criminals.” In armed conflicts between states and international outlaws, or “terrorist organizations” like Hamas, which for many in the West has become a veritable hostis humani generis (enemy of humankind), IHL becomes open to interpretations originally deployed in the context of nineteenth and early twentieth centuries colonial wars with “savage peoples.” The discourse employed by Israeli officials in justifying the indiscriminate use of violence in Gaza also has a legal rationality, chiefly, a permissive interpretation of the principles of distinction and proportionality to rationalize the destruction of Palestinians in Gaza, and not just Hamas, which would amount to war crimes, and crimes against humanity, but that is grounded in a logic that has historically infused IHL and to which the regime is still permeable.